Assessment of Cartosat-1 DEM for Modeling Floods in Data Scarce Regions

Digital Elevation Model (DEM) plays an important role in modeling floods. In data scarce developing countries, unavailability of high resolution topography and river cross-sections data are the prime limitations for simulating hydrodynamic models for modeling floods. In the present study, we assess the quality of Cartosat-1 DEMs in providing accurate river cross-sections and floodplain elevations; and hence their suitability in modeling floods. Cartosat-1 DEMs are prepared using Ground Control Points (GCP) of surveyed elevation and bias corrected Shuttle Radar Topography Mission (SRTM) elevation. Surveyed elevation based Cartosat-1 DEM is found to be of best quality while bias corrected SRTM elevation based Cartosat-1 DEM is found to be of reasonable quality on the basis of cross-section representation as well as elevation statistics. Cross-sections derived from the Cartosat-1 DEMs as well as surveyed cross-sections are later used independently in MIKE11 model for 1-dimensional flow modeling. Simulated water levels from models based on Cartosat-1 DEMs are compared graphically with the observed water levels. Modeling performance is also evaluated using different statistical performance criteria. Results show that the models based on Cartosat-1 DEM derived cross-sections perform similar to the model based on surveyed cross-sections. Study concludes that a reasonably accurate DEM, prepared from moderate survey in data scarce region, can be used for deriving requisite river cross-sections for hydrodynamic modeling.